I bought 2007 V50 1.8 Petrol estate(116,000 miles) recently and I have been having an issue where engine start loosing power and almost knocking until it stalls.
This was happening when I was driving motorway at first. (started to lose power)

Now I could replicate this when I start the engine multiple times.

Here is the video
I am not putting the accelerator down apart from when it's reving up. Computer is trying to idle and not stall.

I took to the garage and they changed the spark plug and battery to brand new ones, and changed oil and filter saying there was no issue.
Garage said battery was charging ok.
This symptom seems to happen when it's hot. (air con is on)

What could this be? There is no Error messages on the dashboard
I am travelling from London to Dorset soon so I am a bit worried,

 

All the warning lights coming on like they did near the end of the video make me suspect a voltage problem. If the battery and alternator are working correctly, it could be a connection between the battery and engine / computers, or a bad computer.

 

Thank you. I am going to Volvo dealer tomorrow in London and mention this.

 

I think the warning lights coming on may be due to the near stall RPMs not allowing the alternator to maintain voltage. The original mechanic (lol the guy who decided to change the oil for an engine that's stalling?) should have scanned for fault codes regardless of what's shown on the display. Did they indicate anything was seen/cleared? As far as possible root causes, its a bit difficult without that added info. I'd be looking at things like fuel pressure/delivery, intake air tubing and air metering (ie the MAF, electronic throttle module), serpentine belt (both the alternator and AC share the drive belt..) for starters. Seems the original tech did check for system voltage but that's not to say that there may be a wonky relay or bad cable that acts up as things get warm.

 

I have a 2007 s60 and I have been have the same problem I tried everything to try and figure out what is causing this misfire in my car. I don't have money to take it to the dealer and I had planled on driving it till it needed to be smogged then just selling it to a junk car place because I did s compression test found out that on cylinder has no compression . I tested plugs ,coils ,injectors wiring all ok. . but even though I had exhausted this whole thing and I had accepted the fact that I have a dead cylinder and that is way out of my price range to fix the car still drives. Sometime the engine light flashes on mr and I slow down to no push the issue . But I am still down to try something even if it seems crazy of it going to not cost much . Well I seen this video for. Pt cruiser.diffent car sure . Same problem dead cylinder or misfire as far as know .I recently only found out my cylinder has no compression at crank. It would seem to me that only a idea the cylinder had no compression. At higher speed it runs fine. Well long story short the guy pulls out the spark plug pours oil in it and puts plug back in , billowing smoke out the tail pipe. It fixed the car . I say the hell with it I'm tryin it .so I buy the stuff.that restores the valves that you pour in the oil. I pull spark plug .it takes me about 3 times to do it. IT WORKS car runs fine. What I gather is if you run the car either with regular oil or it needs a oil change the synthetic oil or regular oil mixes with the gas and when you cut off the engine the last bit of gas washes the cylinder clean and valves start sticking and misfire start happing . It worked so good I pull one by one all my plugs and did them all and I am going to do that once a month. Just Becusse of how much smoother and how much more power my engine seem to have with less strain from the engine